Coherent radio emission from a quiescent red dwarf indicative of star–planet interaction
Coherent radio emission from a quiescent red dwarf indicative of star–planet interaction
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DOI：
10.1038/s41550-020-1011-9
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发表时间：
2020-02
期刊：
影响因子：
14.1
通讯作者：
H. Vedantham;H. Vedantham;J. Callingham;T. Shimwell;T. Shimwell;C. Tasse;B. Pope;M. Bedell;
中科院分区：
文献类型：
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作者：
H. Vedantham;H. Vedantham;J. Callingham;T. Shimwell;T. Shimwell;C. Tasse;B. Pope;M. Bedell;
低频(ν≲ 150 兆赫)恒星射电辐射预计来自外日冕，其高度相当于恒星半径，并大于恒星半径。这种来自太阳的辐射已被用于研究日冕结构、物质抛射和行星周围的空间天气条件。对其他恒星的低频辐射的搜索只发现了一颗活跃的耀斑恒星，并不能代表更广泛的恒星群体。在这里，我们报告了一颗静止的恒星GJ 1151的低频射电辐射的探测。GJ 1151是银河系中最常见的恒星类型(红矮星或光谱类M)的成员。该发射的特征与行星极光发射的特征相似(例如，木星的十米发射)，表明日冕结构由低等离子体密度的全球磁层主导。我们的结果表明，为射电极光提供动力的大范围电流在质量和大气组成的广泛范围内运行，从类地行星到主序恒星。产生观测射电辐射所需的坡印亭通量不是由GJ1151‘S慢自转产生的，而是来自其磁层等离子体与一颗短周期系外行星的亚阿尔夫尼克相互作用。发射特性符合理论上的预期，即与地球大小的行星在大约一到五天的轨道上相互作用。
Low-frequency (ν≲ 150 MHz) stellar radio emission is expected to originate in the outer corona at heights comparable to and larger than the stellar radius. Such emission from the Sun has been used to study coronal structure, mass ejections and space-weather conditions around the planets. Searches for low-frequency emission from other stars have detected only a single active flare star that is not representative of the wider stellar population. Here we report the detection of low-frequency radio emission from a quiescent star, GJ 1151—a member of the most common stellar type (red dwarf or spectral class M) in the Galaxy. The characteristics of the emission are similar to those of planetary auroral emissions (for example, Jupiter’s decametric emission), suggesting a coronal structure dominated by a global magnetosphere with low plasma density. Our results show that large-scale currents that power radio aurorae operate over a vast range of mass and atmospheric composition, ranging from terrestrial planets to main-sequence stars. The Poynting flux required to produce the observed radio emission cannot be generated by GJ 1151’s slow rotation, but can originate in a sub-Alfvénic interaction of its magnetospheric plasma with a short-period exoplanet. The emission properties are consistent with theoretical expectations, , –for interaction with an Earth-size planet in an approximately one- to five-day-long orbit.